1. Field of the Invention
The present invention relates to an image processing apparatus, into which image data is input and in which the input data is processed to produce a high resolution image.
2. Description of the Related Art
The following methods are conventionally known to input a high resolution image or a panorama image:
(1) Method to use a high resolution image pickup device:
A high resolution image may be input by using a high resolution image pickup device as input means of an image processing apparatus.
(2) Method for a line sensor to scan:
This method is a technique in popular use in image scanners, facsimile devices, copiers, or the like mainly as a contact type image scanner, in which each reading operation of a linear CCD sensor obtains a linear image in a horizontal scanning direction and in which the vertical scanning is carried out in a mechanical and optical manner thereby to input image information.
The below Reference 1 describes a trial to obtain a panorama image by the vertical scanning of a noncontact line image sensor in a mechanical and optical manner.
(Ref. 1) Tsuji (Osaka Univ., Faculty of Fund. Engi.) "Panoramic expression of environment", J. of Institute of Electronics, Information and Communication Engineers of Japan (IECEJ), Vol. 74, No. 4, pp 354-359, (1991).
(3) Method using a plurality of image pickup devices
This method is described in the following Reference 2 to Reference 5, in which image information is obtained from a plurality of image pickup devices the relative positional relations of which are known and in which the obtained image information pieces are joined with one another to obtain a high resolution image.
(Ref. 2) Aizawa (Tokyo Univ., Fac. Engi.), Saito and Komatsu (Kanagawa Univ., Fac. Engi.), "Fundamental studies for obtaining ultra high definition image-high definition image acquisition through stereo image processing", IE 90-54 (1990).
(Ref. 3) Uehira (NTT HI Lab.) "High speed still image input method by image pickup region combining method", Briefs 1991 Spring Nat. Conf., IECEJ, pp 7-103.
(Ref. 4) Uehira and Matsuki (NTT) "High speed high definition document reading technique by image pickup region combining method", Briefs 18 1989 Nat. Conf., Inst. Img Electro. Jap. (IIEJ), pp 75-78.
(Ref. 5) Uehira (NTT) "Optical connection type still image camera", J. IIEJ., Vol. 20, No. 3, pp 203-208, (1991).
(4) Method to put images together:
This method is described in the following Reference 6 to Reference 8, in which a plurality of images input in time series are joined together to input a panorama image or a wide range image.
(Ref. 6) Okada, Ohta, and Sakai (Kyoto Univ., Fac. Engi.) "Hand scan type document image input apparatus having real time image joining function", IE 81-17 (1981).
(Ref. 7) Yoshizawa, Hanamura, and Tominaga (Waseda Univ.) "Composition of background image considering panning of dynamic image", Briefs 1990 Spring Nat. Conf., IECEJ, pp 7-51.
(Ref. 8) Nakamura and Kaneko (Tokyo Rika Univ.), and Hayashi (NHK Broadcasting Tech. Lab.) "Production method of panorama image by division image pickup" Briefs 1991 Spring Nat. Conf., IECEJ, pp 7-165.
(5) Method to vibrate an image pickup device:
This method is described in the following Reference 9, in which a CCD image pickup device is vibrated to obtain a doubled resolution image in the vibration direction.
(Ref. 9) Yoshida, Endo, and Harada (Toshiba Inc.) "High resolution process of CCD by swing image pickup", IE 83-65 (1983).
There are, however, the following problems present in the above image input methods.
(a) In the "method to use a high resolution image pickup device" as described in (1) in the above conventional techniques, the number of pixels in an input image depends upon the image pickup device, and, therefore, it is impossible to input an image with the number of pixels more than the capacity of the image pickup device.
(b) In the "method for a line sensor to scan" as described in (2) in the above conventional techniques, the number of pixels in the horizontal scanning direction is limited to that of the line sensor in the same reason as in above (a), and the image alignment cannot be fine without precise mechanical and optical scan in the vertical scanning direction so as to fail to input a fine image.
(c) In the "method to use a plurality of image pickup devices" as described in (3) in the above conventional techniques, the number of pixels is limited to "(pixel number).times.(number of image pickup devices)" in each image pickup device, and the use of the plural image pickup devices inevitably increases the production cost and the scale of image pickup system.
(d) In the "method to join images" as described in (4) in the above conventional techniques, the following problems exist.
In the method as shown in Reference 6, the object image is limited to a binary image, there is a restriction on a direction of scanning performed by an operator, and it is readily influenced by the camera vibration in a direction perpendicular to the scanning direction.
In the method as shown in Reference 7, there is a defect of resolution reduction if two frame images are relatively rotated, magnified, or contracted, because the position alignment is carried out between two frame images only by parallel displacement components between the frames.
In the method as shown in Reference 8, there is a restriction on a positional relation of plural frames, that is, on the displacement amount, the angle, and the like of panning and tilting of camera, and the method is not applicable to parallel displacement of camera, though it is possible to obtain a panorama image as seen from a point.
(e) In the "method to vibrate the image pickup device" as described in (5) in the above conventional techniques, the vibrations are allowed only in one direction, the resolution is at most a double of pixel number of the image pickup device, and a special image pickup device is necessary for accurately synchronizing the amplitude of vibrations with taking-in of image pickup signals.